Subcellular localization of aquaporin 3 in prostate cancer is regulated by RalA

We previously found that in normal epithelia of the prostate, localization of AQP3 is limited to the cell membranes; however, the expression of AQP3 protein in cancer epithelia is distributed to the plasma. Yet, the detailed mechanism remains unclear. In the present study, PC‑3 cell derivatives with stable knockdown of RAS like proto‑oncogene A (RalA) and overexpression of E‑cadherin were established. We found that overexpression of E‑cadherin and knockdown of RaLA resulted in an increase in AQP3 in prostate cancer cell plasma membranes. In order to investigate the functions caused by of the AQP3 redistribution in prostate cancer cells, the growth function of AQP3 redistribution was detected with clonogenic, MTT and MTS assays. In regards to the effect on apoptosis, flow cytometric analysis and DNA Ladder TUNEL assay were utilized. The results showed that AQP3 redistribution in PC‑3 cells significantly inhibited the proliferation of cells and enhanced cell apoptosis compared with these parameters in the control. Wound healing assay and Matrigel assays determined that knockout of RalA inhibited the motility and invasion capability of PC‑3 cells. To investigate the molecular mechanism involved in AQP3 redistribution in PC‑3 cells, the level of cAMP in PC‑3 cells was examined, and the results showed that AQP3 distribution was regulated through cAMP/PKA/RalA signal pathways. In conclusion, these studies suggest a novel function of AQP3, and provide a creative view for RalA-directed therapies.